This is Mazon Monday post #204. What's your favorite Mazon Creek fossil? Tell us at email:[email protected].
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Reconstruction of Psaronius, Illustrated by Auguste Faguet (1877)
Caulopteris sp. are the branch scars of the tree fern Psaronius. Psaronius is an extinct genus of marattialean tree fern. The genus Psaronius is used to describe both the tree trunk and the whole plant. Psaronius tree fern fossils are found from the Carboniferous through the Permian. The foliage of the various species would have been the fronds Pecopteris, Crenulopteris, Sphenopteris, Astrotheca, among others. It might seem odd that individual plant parts have different species names. Paleobotany follows a system called form genera. Form genera is used when the true relationships between fossils is unclear. Form genera are artificial groups of organisms that are grouped together based on morphological resemblance. For example, all fossilized roots of scale trees are assigned to the form genus Stigmaria.
There were four different configurations of branch scars on Psaronius.
Psaronius stem surface petiole base configurations. A. Caulopteris . B. Megaphyton . C. Hagiophyton . D. Artisophyton
The branch scars were first named Megaphyton in 1825 by Edmund Tyrell Artis (1789-1847). Artis was a British geologist, artist, and a pioneer of paleobotany and archaeology. Megaphyton is identified when scars are shown to run in opposing and parallel lines down the length of the branch. Caulopteris was named in 1832 by John Lindley (1799 - 1865) and William Hutton (1797-1860). They wrote a series 3 volumes which described the fossil flora of Great Britain called "The Fossil Flora of Great Britain: of Figures and Descriptions of the Vegetable Remains Found in a Fossil State in this Country".
John Lindley (1799 - 1865) was an English botanist. He was employed early in his career as the assistant librarian to Sir Joseph Banks. In 1822 he became the Assistant Secretary to the Royal Horticultural Society and from 1829 to 1860 he was first Professor of Botany at the University of London and lecturer in botany to the Apothecaries’ Company (1836). He then became a Professor of Botany at Cambridge University. His Report to Treasury and Parliament in 1838 led to the preservation of the Royal Garden at Kew. He described the plants of Mitchell's expeditions to Australia (1838) and an Appendix to the Botanical Register (1839) described plants of the Swan River Colony, Western Australia. His pioneering three-volume work of palaeobotany of England, was first published between 1831 and 1837. The work catalogues almost 300 species of fossil plants from the Pleistocene to the Carboniferous period. The geologist and paleontologist William Hutton (1797-1860), was responsible for collecting the fossil specimens on which the plates were based.
Caulopteris sp appears on page 84 of Jack Wittry's "A Comprehensive Guide to the Mazon Creek Fossil Flora"
Caulopteris sp. Lindley & Hutton, 1832
Megaphyton sp. Artis, 18251825. Megaphyton Artis: p. 20, fig. 20
1832. Caulopteris Lindley and Hutton: p. 121, pl. 42
1955. Caulopteris. Crookall: p. 54
1958. Caulopteris. Langford: p. 129
1976. Caulopteris. Pfefferkorn: p. 9DESCRIPTION: These tree fern trunks have branch frond scars arranged either spirally around the trunk (see Fig. 6) or, more likely, in two opposing and parallel lines down its length (see Fig 1). The scars are more often found individually in Mazon Creek nodules as large, circular, oval, or elliptical coriaceous disks. They have an outer vascular trace which circles inside and more or less follows the outer edge. Inside of that is an inner trace, which can take on many forms, from a straight line to a sideways and stylized C-shape.
REMARKS: Caulopteris scars are very rare and are confined in age to the Westphalian D. This genus has been split into around 100 species. It has now been shown that many of these species-which were mostly based on vascular trace shape are growth stages and do not represent taxonomic differences. Presently, authors prefer to refer to similar forms from a single locality as form-species, e.g., Caulopteris sp. A, B, C, and so forth. All Caulopteris forms are based on the height-to-width ratio of the frond scar. Form A is the roundest, and D the most elongated. Another genus erected for tree fern trunk scars is Megaphyton, which has scars very similar to Caulopteris. The two scars cannot be distinguished when found individually. Megaphyton is used only when it can be shown that the scars occurred on the trunk in two opposing and parallel lines down its length. Due to the relatively small size of Mazon Creek fossils, this is seldom seen.
Specimens
From "A Comprehensive Guide to the Mazon Creek Fossil Flora"
From George's Basement
From Leo Lesquereux's "Atlas to the Coal Flora of the Pennsylvanian and the Carboniferous Formation Throughout the United States", Plate LX
